An example of a conventional stereo-examination system is a stereomicroscope. A beam path of a conventional stereomicroscope is schematically shown in FIG. 1. The stereomicroscope 1 shown there comprises an objective 3 with an optical axis 5 and an object plane 7 in which an object to be viewed is positioned. A beam bundle 11 emanating from the object or object plane 7 into a solid angle region 9 around the optical axis 5 images the objective 3 to infinity and thus converts it into a parallel image-side beam bundle 13. Two zoom systems, each having an optical axis 17 and 18, respectively, of its own, are positioned adjacent each other in the parallel beam bundle 13 such that the optical axes 17 and 18 of the zoom systems are offset parallel to the optical axis 5 of the objective 3 and spaced apart from each other by a distance a. The two zoom systems 15, 16 each feed a partial beam bundle 19 and 20, respectively, out of the parallel beam bundle 13, the partial beam bundle 19 being supplied to a left eye 21 of a user and the other partial beam bundle 20 being supplied to a right eye 22 of the user. To this end, a field lens 23, a prism system 25 and an ocular 27 are disposed in the beam path of each partial beam bundle 19, 20. As a result, the left eye 21 perceives the object 7 at a viewing angle α with respect to the optical axis 5, while the right eye 22 perceives the object at a viewing angle −α with respect to the optical axis. As a result, the user gets a stereoscopic, three-dimensional impression of the object.
FIG. 2 shows part of a beam path of a conventional microscope 1 for providing a stereoscopic image of an object for each one of two users. Similar to the microscope shown in FIG. 1, an objective 3 produces a parallel image-side beam bundle from a beam bundle 11 emanating from the object into a solid angle region, with two zoom systems 15 and 16 being provided, each feeding a partial beam bundle 19 and 20, respectively, out of the parallel beam bundle which are supplied via field lenses 23 as well as prism systems and oculars, not shown in FIG. 2, to the two eyes of a first observer.
In the parallel image-side beam path, there are further disposed two mirrors 31 which feed two further partial beam bundles 33 and 34 out of the parallel beam path and reflect the same such that they extend transversely to the beam direction of the partial beam bundles 19, 20. These two partial beam bundles 33 and 34 are each supplied, via a zoom system 35 and 36, respectively, as well as prism systems and oculars, not shown in FIG. 2, to the two eyes of a second observer.
In order for this microscope to be used by two observers, it is required that, while observing the object, the two observers are constantly in a fixed spatial position relative to the microscope. In particular, if the microscope is used as surgical microscope during a surgical operation, this spatial limitation is obstructive for the two observers who must operate as surgeons in the operating field.